日本人工林达1000万公顷,调查间伐实施状况成为重要的研究课题。但大面积调查造林地几乎是不可能的。日本每5年进行一次全国范围的航空摄影,据报道,树冠郁闭度因间伐而发生的微小变化可用密集网点板测出。为提高测定精度,我们改良了密集网点板,並编制出间伐实行状况的间伐实施图。 Japan’s plantation reached 10 million hectares, the investigation of the implementation of thinning has become an important research topic. However, a large area survey of afforestation is almost impossible. Japan conducts nationwide aerial photography every five years, and tiny changes in canopy crown closures have been reported as dense dot-board changes. In order to improve the accuracy of the measurement, we have improved the dense dot board and prepared the thinning implementation map of the actual implementation of thinning.